<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>If...else 语句</title>
</head>

<body>
    <p>点击这个按钮，获得基于时间的问候。</p>
    <button onclick="myFunction()">点击这里</button>
    <p id="demo"></p>
    <script>
        function myFunction() {
            var x = "";
            var time = new Date().getHours();
            if (time < 20) {
                x = "Good day";
            }
            else {
                x = "Good evening";
            }
            document.getElementById("demo").innerHTML = x;
        }
    </script>
</body>

</html>